It is known in the state of the art to use ventilation apparatuses on board various types of aircraft, in particular on board airplanes.
In general, these ventilation apparatuses are used to cool different pieces of onboard equipment, for example onboard computers, or other types of devices equipping those aircraft.
To that end, such a ventilation apparatus includes a rotary machine powered by an electric power grid of the aircraft and a fan wheel secured to the rotor of the rotary machine. The fan wheel is for example formed by a propeller and is positioned in an air duct emerging outside the aircraft.
Thus, when the ventilation apparatus is turned on, i.e., when the rotary machine is connected to the electric grid, the fan wheel suctions cool air from outside the aircraft toward a heat exchanger to cool the corresponding onboard equipment.
This type of cooling, also called forced ventilation, is more particularly used when the aircraft is on the ground. In that case, various monitoring means may be used to monitor the operation of the ventilation apparatus, and if an anomaly is detected, to generate a corresponding alarm. These monitoring means are generally powered by an electric current from the electric grid of the aircraft.
When the aircraft is in flight, its movement speed is generally sufficient to create a natural air flow in the duct due to the movement of the aircraft in the mass of air, and the operation of the ventilation apparatus is no longer necessary. In those cases, the ventilation apparatus is disconnected from the power grid and the monitoring means are inactive.
However, it is often necessary to monitor the ventilation apparatus in order to detect and/or avoid damage thereto when it is not powered.